Assessment of Consistency of
Census Results with
Demographic Benchmarks

This report assesses the accuracy of the Census 2000 Dress Rehearsal
results for Sacramento City, Menominee County, and the Columbia, South
Carolina site. We examine the consistency of housing and population
totals with independent benchmarks for each site. We assess the
consistency of key demographic characteristics, such as persons per
household, age/sex distributions, race/Hispanic origin distributions,
vacancy rates, and group quarters population.

The dress rehearsal census results pass most tests of demographic
consistency. For all three sites, the demographic characteristics
examined agree with past census data and expected trends.

For Sacramento City, the released census population total of 403,313 is
confirmed by independent demographic estimates adjusted for net
undercount. Further, the underlying Integrated Coverage Measurement (ICM)
estimate of net undercount (6.3 percent) is validated by the independent
benchmarks. Without the ICM adjustment, the census result for Sacramento
City would be too low.

For Menominee County, Wisconsin, the released census population total of
4,738 is confirmed by independent demographic estimates adjusted for net
undercount. The underlying ICM estimate of net undercount (3.0 percent)
is broadly validated by the independent benchmarks.

For the South Carolina site, the census housing and population totals fall
below expected levels. Population coverage in 1998 declined relative to
1990--attributable in large part to the incompleteness of the address list
and the resulting shortfall of census housing units. The large
undercoverage in the dress rehearsal results for the site was measured by
the Post Enumeration Survey and validated by the demographic benchmarks.

In reaching this assessment, the demographic evaluation answers the four
broad questions set forth in the September 15, 1998 outline of the C7
report:

2) Are there coverage problems associated with the 5-person questionnaire?

NO. The distribution of the number of persons per
household is consistent with historical trends and changes
in the composition of the population. Similarly, when the
proportion of households with 6 or more persons is
compared to the proportion with 5 persons, the results do
not point to coverage problems. It should be noted that this
assessment is a face validity check. Tests of statistical
significance of differences were not performed.

3) Do the independent demographic benchmarks provide
early indications of the magnitude of coverage errors?

YES. The dress rehearsal data were evaluated in sequential
comparisons. Early assessment of the Decennial Master
Address File suggested a shortage in the number of housing
units in the South Carolina site. The demographic
indicators gave an early assessment of the magnitude of the
population undercount in each site. All the demographic
benchmarks signaled the decline in coverage in the South
Carolina site relative to 1990.

4) Are the subnational demographic tools effective in
validating the census results for geographic areas in a
manner similar to the traditional national Demographic
Analysis estimates?

YES. In every census since 1950, demographic analysis
has played an important role in evaluations of data quality
and in assessments of completeness of coverage at the
national level. The dress rehearsal demonstrated the
application of the demographic benchmark approach at the
subnational level. Postcensal housing and population
estimates and data from previous censuses were used as
demographic benchmarks to examine data consistency and
coverage errors at the site and county level. The
demographic approach provided important independent
benchmarks to validate the census and ICM results.

The results were available internally shortly after the
release of the various census data files and in time for
inclusion in status reports.

It is recommended that the demographic evaluation of Census
2000 start with the release of the Decennial Master Address File
in the summer of 1999. The evaluation should examine the
accuracy of the housing unit count based on this file with
independent housing benchmarks and historical census data. A
coverage assessment before Census Day will provide an
opportunity to take corrective actions when necessary.

It is further recommended that in Census 2000 the demographic
evaluation approach extends to the subnational level (state and
county). Traditionally, demographic analysis has been used to
assess the accuracy of the census results and the magnitude of
population undercoverage at the national level. This
demographic evaluation of the dress rehearsal sites and the
earlier evaluation of the 1995 Census Test demonstrate that an
expanded demographic analysis program could be a timely,
inexpensive, and operationally feasible coverage evaluation tool
for Census 2000.

Section 1. Background

This report assesses the Census 2000 Dress Rehearsal
results for Sacramento City, Menominee County, and the
Columbia, South Carolina site. The study is designed to
answer the following four questions posed in the
September 15, 1998 outline of this report (Robinson,
1998):

1. When compared to a battery of independent benchmarks
and demographic tools, do the census population and
housing distributions look plausible (e.g., age, sex, race
distributions, household distributions, vacancy rates, group
quarters population)?

2. Is there a discrepancy between the proportion of 5-
person and 6-person or more households in the census
results that suggests coverage problems associated with the
5-person questionnaire?

3. Do the differences between the census estimates and
independent benchmarks inform us early (September-
October of 1998) about the magnitude of undercount that
will be measured by the Integrated Coverage Measurement
(ICM)?

4. Are the subnational demographic analysis (DA) tools
effective in validating the census and ICM results for
geographic areas, in a manner similar to the traditional use
of national DA coverage estimates?

This study represents an extension of the demographic
analysis program the Census Bureau has used for many
years to evaluate the accuracy of census results and
completeness of coverage at the national level (see Siegel,
1974, Fay et al, 1988, and Robinson et al, 1993). The
application of demographic techniques to evaluate
coverage of subnational areas was successfully used as part
of a comprehensive evaluation of the quality of the 1995
test census results for Oakland, CA, Paterson, NJ, and 6
parishes in Louisiana (see Robinson, 1996a, 1996b, and
Kohn, 1996).

Section 2. Methodology

We employ a battery of demographic tools to assess the
Census 2000 Dress Rehearsal results. These include
population, housing, and group quarters (GQ) estimates,
vacancy rates, school enrollment data, Medicare data, sex
ratios, age distributions, household distributions, and
race/origin distributions. The tools are obtained from
different sources.

The Census Bureau produces annual postcensal estimates
of total population by the component method of
demographic analysis. The component method updates the
decennial population count for an area by taking into
account net demographic change. This change is obtained
by adding births, subtracting deaths, and adding estimates
of net domestic migration and international immigration. It
should be noted that no adjustments are made for the
estimated net population undercount in the census. The
number of births and the number of deaths are based on
reported vital statistics for each county. Estimates of legal
immigration from abroad is estimated using data obtained
from the Immigration and Naturalization Service.
Emigration and undocumented immigration are estimated
using analytic methods. Internal migration, or migration to
and from other counties in the United States, is estimated
from two different administrative records and in separate
estimations for the age groups under and over age 65. For
the population under 65, a year to year match of federal
income tax returns is used to determine migration between
counties. For the population age 65 and over, the change in
Medicare enrollment figures is used to produce the
migration estimates. For more details see Appendix B.

The housing unit estimates are produced by the Census
Bureau by adding new construction (permit and non-
permit) and new mobile homes to the previous years
housing stock and subtracting demolitions (permit and non-
permit). School enrollment and Medicare data are obtained
from administrative files. Sex ratios, age distributions and
similar measures are examples of demographic measures
obtained through statistical manipulations of the data.

An important element of the evaluation is its sequential
nature. The census estimates are evaluated at four points in
time: housing counts from the Master Address File (MAF);
initial phase estimates from the Census Unedited File-CUF;
post-Nonresponse Follow-up (NRFU) estimates from the
Census Edited File-CEF; and final census estimates that
include the ICM component (for Sacramento and
Menominee only). The improvement in data quality and
coverage completeness is systematically assessed through
these sequential comparisons.

In this report, we focus on the last two stages--the housing
and unadjusted population numbers from the CEF and
the final adjusted population results that include the ICM
component. Previous memoranda have reported on the
MAF and the CUF stages. These analyses and other
evaluations are available on request.

First, we examine the consistency of the final census
population results for Sacramento and Menominee with
independent benchmarks adjusted for net undercount
(Table 1). For the South Carolina site, we assess the
consistency of the census population total with the
independent benchmark (Table 2). We also evaluate
census estimates adjusted for net undercount with the Post
Enumeration Survey (PES) estimates.

Second, we examine the consistency of the housing totals
with independent benchmarks for each of the three sites.
The housing counts are examined in Table 3.

Next, we assess the consistency of key demographic
characteristics, such as the GQ population, vacancy rates,
persons per household, age/sex and race/Hispanic origin
distributions. Tables 4-8 and Figures 1-2 make
comparisons of these demographic characteristics over
several censuses.

Finally, we demonstrate how the population estimates are
used to make some inferences about the magnitude of
population undercoverage independently--and in advance--
of the ICM coverage results. In Table 9, the population
estimates are benchmarked on 1990 adjusted counts (as
measured by the PES estimates) and carried forward to
1998. The adjusted population estimates have two
evaluative purposes: (1) to provide an early assessment of
the magnitude of undercoverage in the initial census
results, and (2) to broadly validate the ICM/PES results.
We also examine sex ratios and other data for the South
Carolina site to make additional inferences about
differential undercoverage (Tables 10-12 and Figures 3-4).

It is important to note that the methodology of the
demographic estimates is entirely different from that of the
ICM coverage estimates. The ICM (Dual-System
Estimates) are survey-based estimates. As described
above, the demographic estimates are based largely on
aggregate administrative data (and past census data for
some benchmarks) statistical samples are not the
foundation of the estimates. The demographic estimates
are essentially independent of the census and the errors are
of a different nature than those of the ICM survey estimates
being evaluated.

Section 3. Limitations

It should be kept in mind that the reported findings are
generally descriptive. Due to uncertainty about the quality
of the components that are used to construct the
independent estimates and assumptions about migration,
the demographic measures may at best provide only rough
indicators of differential undercoverage in 1998 and change
in coverage historically for the sites.

Another limitation of this study is the lack of accepted
statistical basis to assess the accuracy of the independent
population estimates or other benchmarks. Until some
uncertainty models are developed, the demographic results
can be considered only "face validity" indicators.

Despite these limitations, the consistency of the findings
across a variety of different demographic benchmarks (e.g.,
previous census results, current population and housing
estimates from different sources, sex ratios, use of school
enrollment data and medicare data) provides some check
on the reasonableness of the estimates. Furthermore, the
demographic approach has the distinct advantage of being
operationally feasible, timely, and cost effective.

Section 4. Results

1. Consistency of Population Totals with Independent
Benchmarks

We first evaluate the consistency of the results for the
Sacramento City and Menominee sites, where all census
activities were conducted (including sampling for
nonresponse followup and adjustment for net
undercoverage). We then evaluate the results for the South
Carolina site, where sampling was not used for
nonresponse followup and the released census figures do
not include an adjustment for net undercount.

* Sacramento City, CA and Menominee County, WI:

Table 1 compares the Census 2000 Dress Rehearsal results
for Sacramento City and Menominee County with
independent estimates (the initial independent estimates
have been adjusted for net undercount). The census
population results (released on January 14, 1998) are
shown in column 4. Two separate components of the
census results are also shown for this evaluation--the initial
phase census estimate (col. 1) and the ICM estimate of net
undercount (col. 2-3).

For each site, two different independent estimates are
compared to the released census population totals. These
comparisons allow us to apply face validity checks to the
census and ICM/PES results. One of the estimates is
derived from the Census Bureau's population estimates
program; the other is derived from agency estimates in
each State (the adjustment of the Census Bureau and
agency population estimates for net undercount is shown in
Table 9).

a) Sacramento City, CA:The census
population estimate of 403,313 (col. 4) is consistent
with the range of the demographic estimates adjusted for
net undercoverage (391,557 to 405,123). The underlying
ICM estimate of net undercount (6.3 percent) is validated by
the demographic benchmarks (implied undercoverage of 3.5 to
6.8 percent). Without the ICM adjustment, the initial census
estimate (377,741) would be too low.

b) Menominee County, WI:The census population
estimate of 4,738 is broadly consistent with the range of the
demographic estimates adjusted for net undercoverage
(4,742 to 5,191). The underlying ICM estimate of net
undercount (3.0 percent) is at the low end of the broad
range of demographic undercoverage indicators (3.1 to
11.5 percent). The wide range in the demographic numbers
reflects the wide range in the independent estimates for
such a small area.

* South Carolina Site:

Table 2 evaluates the Census 2000 Dress Rehearsal results
for the South Carolina site. Included in the table is the
released census population total (col. 1), the PES estimate
of net undercount (col. 2-3), and the adjusted population
estimate (col. 4). This adjusted estimate is compared to the
adjusted independent estimate (col. 5).

The census population result of 662,140 is below expected
levels as measured by both the 1998 PES and demographic
benchmarks. The population net undercoverage estimated
by the PES is 9 percent. This result is broadly consistent
with the undercoverage for the South Carolina site implied
by the demographic estimate (about 7 percent). Both sets
of estimates indicate a decline in population coverage from
1990 (PES estimate of 2.3 percent net undercount--see
Table 9).

These findings of population undercoverage in the South
Carolina site are consistent with the later analysis of
administrative data (Medicare, school enrollment, birth
statistics) that indicate a decline in coverage between 1990
and 1998 (see Section 4). The population shortfall is
related to a shortfall in housing (see next section).

2. Consistency of Housing Totals with Independent
Benchmarks

Table 3 provides a comparison of the Census 2000 Dress
Rehearsal results (col. 3) with independent housing
estimates produced by the Census Bureau and by State
agencies (col. 2). Percent differences for housing units are
shown in column 5. The South Carolina results are
reported for the site and for each county separately. For
reference, results from the 1990 Census are provided in
column 1.

It should be noted that the housing data are not adjusted for
net undercoverage. The adjustment of undercount in the
Dress Rehearsal results was applied to population totals
only.

* Sacramento City, CA:The 1998 census
housing total is lower than the independent estimates.
The census housing unit total is below both the Census Bureau
and the California Agency estimate (by 0.5 and 1.9 percent)--but
the margin of error in the independent estimates could be
this large.

* Menominee County, WI:The 1998 census
housing total is higher than the independent estimate.
The housing unit count is higher than expected (6.9%), but we
cannot make any reliability statements given the imprecision
in the independent estimate for such a small site.

* South Carolina Site:The 1998 census
housing total falls consistently below the independent estimates,
with the housing shortfall exceeding 10 percent in one county.
The shortage of housing units is reflected in the population
shortfall for the site.

For the total site, the census housing total is 5.6 percent
below the independent estimate. All counties have fewer
housing units than estimated; the shortage exceeds 7
percent in three counties (Marlboro, Newberry, and
Union). These differences can be large enough to lead to
contrasting trends in housing growth since 1990--the 1998
census results imply housing loss in Marlboro and Union
counties whereas the independent estimates indicate
expected housing growth. The finding of a low housing
count in the South Carolina site is consistent with the
results of other Census 2000 Dress Rehearsal evaluations.

The housing deficiency is somewhat surprising given that
the Master Address File (MAF) total was higher than our
independent estimate (West and Robinson, 1998).
Analysis of housing data from the Census Unedited File
shows that high levels of deleted units may be in part
responsible for this drop. We need to assess the types of
housing units included on the MAF extracts used to mail
out the census questionnaires and visit the nonresponding
units.

3. Consistency of Key Demographic Characteristics

In the previous two sections we focused on the consistency
of housing and population totals. Now we examine the
consistency of housing and population distributions within
those totals.

Tables 4-8 and Figures 1-2 provide an historical
comparison of the Census 2000 Dress Rehearsal results
with census data on six statistics: (1) percent population in
group quarters, (2) vacancy rates, (3) persons per
household (PPH), (4) age distributions, (5) race
distributions and (6) Hispanic origin distributions. Table 4
shows data on the group quarters (GQ) population, vacancy
rates and persons per household. Data are shown for 1998,
1990 and 1980. The county level data are shown in Table
5. The percent distribution of households by number of
persons per unit are summarized in Table 6 (1980-1998).
Table 7 displays the census distributions classified by race
(1970-1998). Table 8 shows distributions classified by
Hispanic origin (1980-1998). Age distributions are
examined in Figures 1 and 2 (1990, 1998).

* All three sites (Sacramento City, Menominee County,
and South Carolina Site):

For all the sites, the aforementioned statistics exhibit
consistency with previous census data and expected trends.

a) Group Quarters--Historically, the GQ
population has been large in the South Carolina site
(especially in Richland County). The GQ counts appear
consistent with results from previous censuses (cols. 2 and 3
of Table 4). Deviations such as the observed increase in the
remaining counties in the South Carolina site may be explainable
(e.g., construction of prisons--see GQ data for Lancaster,
Lee, and Marlboro counties in Table 5).

b) Vacancy rates--The vacancy rates also show
consistency across censuses (Table 4, col. 6). For example,
the rate in Menominee County is very high (33.7%), but is
similar to the rate in previous censuses (38.1 and 39.8%).
Some changes are noted. For example, in Sacramento, the
vacancy rate in 1998 was higher than the vacancy rate in
1990, but similar to the rate in 1980. The vacancy rates
have edged up in the counties in the South Carolina site
(8.3% in 1990 to 10.1% in 1998). As seen in Table 5, this
increase is especially large in five counties (Chester,
Chesterfield, Darlington, Lee, and Marlboro).

c) Persons per household--Household
distributions are important to examine for two reasons: (1)
broad trends in the number of persons per household are
predictable, and (2) discrepancies in the proportion of
households of certain sizes may point to questionnaire design
problems. For example, a sharp drop in the proportion of
households with 6 or more persons compared to 5 persons may
suggest coverage problems associated with the 5-person
questionnaire. Examining the dress rehearsal results (Table
6), we find that the trends in PPH pass the first test of
consistency--the increasing average size per housing unit in
Sacramento (2.39 in 1980 to 2.50 in 1990 and 2.52 in
1998) may be attributed to increased proportions of Asian,
Hispanic, and immigrant households in the city. The
declining PPH in Menominee and South Carolina for 1998
is consistent with the declines in previous censuses and
expected patterns since 1990.

Furthermore, the data in Table 6 do not reveal any
evidence of inconsistent 4, 5, 6, and 7 or more person
household distributions over the 1980 to 1998 period. The
distributional trends are generally in line with those
expected based on the overall change in persons per
household discussed above. In Menominee, there was a
sharper than expected drop in the number of 6 person
households compared to the number of 5 person
households, but the overall number of observations is too
small to arrive at any firm conclusion.

d) Age Distributions--Age is an important demographic
characteristic, which changes in a very predictable fashion.
Figure 1 displays the single-year-of-age distribution for
each site in 1990 and 1998. The profile of the 1998 data
generally conforms to the 1990 distributions and reflect the
same variability. The "movement" in the population
profiles for 1990 and 1998 between ages 40 and 50 is real
(see Sacramento and South Carolina profiles)--it is the
aging of the leading edge of the baby boomers. The
consistency of the age distribution is much clearer when
the 1990 and 1998 data are aligned on the basis of birth
cohorts (Figure 2).

e) Race Distributions--Table 7 displays census population
results classified by race. It is important to look at the
consistency of race data given the new race questions in the
dress rehearsal, where respondents could report more than
one race. The last column of Table 7 gives the number of
persons in each site who reported two or more races; the
other columns reflect single race responses.

Three observations from Table 7 are noted here. First,
multiple race reporting was more frequent in Sacramento, a
city with a very diverse race and ethnic composition.
Slightly over 5 percent of the population is classified in this
category (5.4 percent, or 21,965 persons). Multiple
reporting accounts for 1.2 percent (59 persons) in
Menominee County and 0.8 percent (5,628 persons) in the
South Carolina site.

Second, with one exception (see following paragraph), the
race distribution in 1998 in each site is consistent with
historical trends and shifts expected on the basis of
migration patterns since 1990. For Sacramento and South
Carolina, the decreasing proportions of Whites and
increasing proportions of other racial groups in 1998
reflects the continuation of long-standing trends (the
decline for Whites in 1998 is attributable in part to
reclassification into the "2 or more" category). For
Menominee County, the race distribution is fairly constant
over time.

The one exception concerns the increase in the number of
persons classified as American Indian and Alaskan Native
in Sacramento City. In 1998, this category included 12,327
persons, or 3.1 percent of the total population. In 1990, the
number was 4,561, or 1.2 percent of the total. Factors
leading to this significant increase are being studied.

f) Hispanic Origin Distributions--The population
distributions classified by Hispanic Origin also exhibit
consistency across censuses (Table 8). The increasing
proportions of Hispanics in Sacramento is a result of
domestic in-migration and immigration. The Hispanic
population remains relatively small in Menominee County
and the South Carolina site, reflecting the absence of strong
migration trends.

4. Early Demographic Inferences about the Magnitude
of Undercoverage

The independent estimates shown in Table 9 are
benchmarked on 1990 adjusted counts (as measured by the
1990 PES estimates carried forward to 1998). The
differences from the unadjusted census numbers (col. 9) for
each dress rehearsal site reflects an accounting for both the
estimated undercount in 1990 and change in coverage in
the dress rehearsal results. We also examine sex ratios and
other data to make additional inferences about differential
undercoverage in the South Carolina site (Tables 10-12 and
Figures 3-4).

The adjusted population estimates are used in this
evaluation phase to provide an early assessment of the
magnitude of undercoverage in the initial census results.
This independent coverage assessment was available in
advance of the ICM/PES coverage results. As already
described, these early demographic coverage indicators
also validated the sample survey-based coverage estimates.

* Sacramento City, CA:A population
undercoverage of 3 to 7 percent in the dress rehearsal
initial-phase results is implied by the alternative
adjusted population estimates
(3.5% for the Census Bureau estimate, 6.8% for the
California Agency estimate). These figures are generated
by applying the 3.0 percent PES undercount adjustment in
1990 to the Census Bureau estimate and the California
Agency estimate (col. 3) and estimated demographic
change for 1990-98 (col. 5). The range in the implied
undercoverage (col. 9) reflects the difference in the two
independent estimates for the city (col. 6).

* Menominee County, WI:A population
undercoverage of 3 to 11 percent in the dress rehearsal
initial-phase results
(11.5% for the Census Bureau estimate, 3.1% for the
Wisconsin Agency estimate). These figures are generated
by using a 10.0 percent undercount adjustment in 1990 and
applying it to the Census Bureau estimates and the agency
estimate (col. 3) and estimated components of change for
1990-98 (col. 5). The wide range in the implied
undercoverage (col. 9) reflects the wide range in the
independent estimates for small areas.

* South Carolina Site:A population
undercoverage of about 7 percent in the dress rehearsal
result is implied by the adjusted population estimate
(7.0% for Census Bureau
estimate; separate estimates are not available from the
South Carolina agency). This number is a product of the
2.3 percent PES undercount adjustment in 1990 (col. 3) and
estimated 1990-98 change (col. 5). The difference of the
adjusted independent estimate and the dress rehearsal result
is greater in the ten counties surrounding Richland County
(8.2%) than in Richland County itself (5.6%). The
difference exceeds 10 percent in three counties (Chester,
Marlboro, and Union).

We have examined other demographic data to understand
better and verify the decline in coverage indicated for the
South Carolina site. First, we examine sex ratios to make
inferences about the coverage of specific groups. Figure 3
displays the sex ratios (males per 100 females) of Blacks
and Whites in the 1990 census and the Census 2000 Dress
Rehearsal (unadjusted census data). Relative to Whites,
the sex ratios for Blacks are low--indicative in part to the
high undercount of black men as documented by the
previous national DA estimates. Differential sex ratios also
result from factors such as differential mortality and
differences in migration patterns, but no doubt the
differential high undercount of black men is again a
factor--a differential the ICM/PES is designed to reduce. The
"gap" between the sex ratios for Blacks and Whites in fact
increased from 1990 to 1998 for the South Carolina site.

Figure 4 compares the sex ratios for the 1998 South
Carolina results based on two sets of data--one using the
unadjusted census data and the other using PES-adjusted
census estimates. The sex ratios for Blacks based on the
adjusted data are higher and move closer to the sex ratios
for Whites, thus indicating that the PES adjustment results
in the reduction of the differential undercount for Blacks.

Second, we compare coverage levels in 1990 and 1998
implied by different data sources: Medicare data to assess
relative coverage of the population 65 and over; school
enrollment data to infer relative coverage of the population
aged 7 to 14, and birth statistics and migration estimates to
assess relative coverage of the population under age 10
(Tables 10-12). The comparisons for each age group are
consistent in indicating a decline in coverage from 1990 to
1998 in the South Carolina site. For example, Table 10
shows that the ratio of the enumerated population 65 and
over to the Medicare-enrolled population declined from
102.2 in 1990 to 98.2 in 1998. The ratio of enumerated
children 7-14 to the school enrolled population declined
from 97.0 in 1990 to 94.9 in 1998 (Table 11).
Demographic indicators of net coverage for ages under 10
based on birth statistics and migration estimates decreased
from 96.3 percent coverage in 1990 to 93.1 in 1998 with
the coverage of black children being lower than for other
races (Table 12). These findings of a coverage shortfall for all
ages would be expected if the undercount is attributable in
large part to missed housing units.

Section 5. Conclusions/Recommendations

The dress rehearsal results pass most tests of demographic
consistency. For all three sites, the demographic
characteristics examined (such as persons per households,
race/Hispanic origin distributions, and vacancy rates)
conform with past census data and expected trends.

For Sacramento and Menominee, the housing and
population totals are broadly consistent with independent
estimates. For Sacramento City, the released census
population total of 403,313 is confirmed by independent
demographic estimates adjusted for net undercount.
Further, the underlying Integrated Coverage Measurement
(ICM) estimate of net undercount (6.3 percent) is validated
by the independent benchmarks. Without the ICM
adjustment, the census result for Sacramento City would be
too low.

For Menominee County, Wisconsin, the released census
population total of 4,738 is confirmed by independent
demographic estimates adjusted for net undercount. The
underlying ICM estimate of net undercount (3.0 percent) is
broadly validated by the independent benchmarks.

For the South Carolina site, the housing and population
totals fall consistently below expected levels. Population
coverage in 1998 declined relative to 1990--attributable in
large part to incomplete address lists and thus, the shortfall
of census housing units. The undercoverage in the dress
rehearsal results implied by the demographic benchmarks
are consistent with the undercoverage measured by the PES
results for the South Carolina site.

In reaching this assessment, the demographic evaluation
answers the four broad questions set forth in the September
15, 1998 outline of the C7 report:

Are the overall results plausible? YES

Are there coverage problems associated with the 5-person
questionnaire? NO

Do the independent demographic benchmarks provide
early indications of the magnitude of coverage errors?
YES

Are the subnational demographic tools effective in
validating the census results for demographic areas in
a manner similar to the traditional national
Demographic Analysis estimates? YES

Recommendations:

1) Evaluate completeness of MAF

The finding of a low housing unit count in the South
Carolina site is consistent with the results of other Census
2000 Dress Rehearsal evaluations. A number of important
questions can be asked. Is the housing shortfall a
consequence of housing units being missed in the MAF?
Were the units in the MAF, but erroneously deleted in
census operations? Why was the housing shortfall more
pronounced in the South Carolina site than in the other
sites? Since the completeness of housing is critical to the
success of any census, we need to thoroughly assess the
quality of the MAF and other activities that affect housing
coverage. The demographic evaluation can start in the
summer of 1999 with the release of the Decennial Master
Address file.

2) Conduct expanded demographic evaluations in Census
2000

Despite the inherent limitations of the demographic
estimates, the battery of demographic and analytic tools
described here provides an important independent basis to
assess the accuracy of the census results and the magnitude
of undercoverage. This demographic evaluation of the
dress rehearsal sites and the earlier evaluation of the 1995
Census Test demonstrate how an expanded demographic
analysis program could be a timely, inexpensive, and
operationally feasible coverage evaluation tool for Census
2000 at the state and county levels.

Section 6. References

Fay, Robert, Jeffrey S. Passel, and J. Gregory Robinson.
1988. "The Coverage of Population in the 1980 Census,"
Evaluation and Research Reports. PHC80-E4. U.S.
Bureau of the Census.

Kohn, Felipe. 1996. "Evaluation of Reduction in
Differential Undercount Based on the Analysis of Sex
Ratios." Integrated Coverage Measurement (ICM)
Evaluation Project 13. U.S. Bureau of the Census.

__________________. 1996b. "Demographic Review of
the Housing and Population Results of the 1995 Test
Censuses." Memorandum to Arthur J. Norton, Chief,
Population Division, U.S. Bureau of the Census.

Robinson, J. Gregory, Ahmed, B.; Das Gupta, P.; and
Woodrow, K. A. 1993. "Estimation of Population
Coverage in the 1990 United States Census Based on
Demographic Analysis," Journal of the American
Statistical Association, Vol. 88, No. 423, p. 1061-1071.

Robinson, J. Gregory and Edward L. Kobilarcik. 1995.
"Identifying Differential Undercounts at Local Geographic
Levels: A Targeting Database Approach." Paper
presented at the Annual Meeting of the Population
Association of America, San Francisco.

Siegel, Jacob S. 1974. "Estimates of Coverage of
Population by Sex, Race and Age: Demographic
Analysis." Evaluation and Research Program. PHC(E)-4.
U.S. Bureau of the Census.

West, Kirsten K., and J. Gregory Robinson. May 11, 1998.
"Preliminary Assessment of the Completeness of the
Master Address File." Memorandum prepared for John F.
Long.

Sources:
Col. 1: Revised data from 1990 Census. Revisions include post-1990 Census
corrections of political geography or geographic mis-allocations and boundary
updates. Three counties in the South Carolina site are affected: Chesterfield,
Marlboro, and Richland.
Col. 2: Independent housing estimates for dress rehearsal Census Day (4-18-98).
See Appendix C Table 1 for derivation.
Col 3: From Dress Rehearsal results available on Census Bureauís Internet site
(www.census.gov).
Note: The housing data are not adjusted for net undercount. The ICM adjustment is
applied to population totals only (such as Table 1, col. 2-4). The housing data
for Irmo town in Lexington County is included in the South Carolina site total and
ĎOther Countyí total, but is not shown separately.

Table 4. Comparison of Census 2000 Dress Rehearsal Results on
Housing and Population with Previous Censuses: Group Quarters (GQ's),
Vacancy Rates, and Persons Per Household

Site and Year

Group Quarters

Vacancy

Persons Per Household

Total
Population
(1)

GQ
Population
(2)

Percent
GQ
(3=2/1)

Housing
Units
(4)

Vacant

(5)

Percent
Vacant
(6=5/4)

House-
holds
(7=4-5)

HH
Population
(8)

Persons
per HH
(9=8/7)

Sacramento City, CA

Census 4-18-98 [1]

403,312

8,307

2.1%

158,281

11,698

7.4%

146,583

369,434

2.52

Census 4-1-90

369,365

8,138

2.2%

153,362

8,918

5.8%

144,444

361,227

2.50

Census 4-1-80

275,741

6,190

2.2%

123,284

10,425

8.5%

112,859

269,551

2.39

Menominee County, WI

Census 4-18-98 [1]

4,779

45

0.9%

2,046

690

33.7%

1,356

4,550

3.36

Census 4-1-90

3,890

36

0.9%

1,742

663

38.1%

1,079

3,854

3.57

Census 4-1-80

3,373

0

0.0%

1,327

528

39.8%

799

3,373

4.22

South Carolina Site

Census 4-18-98

662,140

33,524

5.1%

273,497

23,608

8.6%

249,889

628,616

2.52

Census 4-1-90

654,115

30,717

4.7%

253,292

19,856

7.8%

233,436

623,398

2.67

Census 4-1-80

628,016

35,777

5.7%

221,036

18,001

8.1%

203,035

592,239

2.92

Richland County

Census 4-18-98

296,709

25,278

8.5%

119,214

8,064

6.8%

111,150

271,431

2.44

Census 4-1-90

285,720

26,091

9.1%

109,564

7,974

7.3%

101,590

259,629

2.56

Census 4-1-80

269,735

33,009

12.2%

91,912

6,451

7.0%

85,461

236,726

2.77

Other Counties (Total)

Census 4-18-98

365,431

8,246

2.3%

154,283

15,544

10.1%

138,739

357,185

2.57

Census 4-1-90

368,395

4,626

1.3%

143,728

11,882

8.3%

131,846

363,769

2.76

Census 4-1-80

358,281

2,768

0.8%

129,124

11,550

8.9%

117,574

355,513

3.02

Note:

[1] The Total Population (col. 1) figures differ from those in Table 1 (col.4) because of rounding and Census Bureau
procedures for handling overcounts. These differences will not occur in Census 2000.

Sources:
Col. 1, 2, 4, 5:
1998 Data: From Dress Rehearsal results available on Census Bureauís
Internet site (www.census.gov). The total population estimates for
Sacramento City and Menominee County in col.1 include the adjustment for net undercount. The population results for the South
Carolina site do not include the net undercount adjustment. The data on GQ population (col.2), housing units (col.4), vacant
(col.5), households (col.7) and household population (col.8) are not adjusted for net undercount. The ICM adjustment is
applied to population totals only (such as the Sacramento total of 403,312 and Menominee total of 4,779 in col.1).

1980 and 1990 Data: 1980 and 1990 census tabulations. The population and housing data for 1990 are based on unrevised data
(see footnote to Table 3). The population and housing data for 1990 and 1998 do not include adjustment for net undercount.

See Table 5 for the data pertaining to each of the other 10 countiesand Irmo town (Lexington County) in the South Carolina site.

Table 5. County Level Comparison of Census 2000 Dress Rehearsal
Results on Housing and Population with Previous Censuses: Group Quarters
(GQ's), Vacancy Rates, and Persons Per Household

County and Year

Group Quarters

Vacancy Rates

Persons Per Household

Total
Population
(1)

GQ
Population
(2)

Percent
GQ
(3=2/1)

Housing
Units
(4)

Vacant

(5)

Percent
Vacant
(6=5/4)

House-
holds
(7=4-5)

HH
Population
(8=1-2)

Persons
per HH
(9=8/7)

Chester

Census 4-18-98 [1]

30,487

250

0.8%

12,677

1,170

9.2%

11,507

30,237

2.63

Census 4-1-90

32,170

118

0.4%

12,293

845

6.9%

11,448

32,052

2.80

Census 4-1-80

30,148

96

0.3%

10,737

761

7.1%

9,976

30,052

3.01

Chesterfield

Census 4-18-98

39,666

549

1.4%

17,316

1,968

11.4%

15,348

39,117

2.55

Census 4-1-90

38,577

380

1.0%

15,100

1,054

7.0%

14,046

38,197

2.72

Census 4-1-80

38,161

116

0.3%

13,927

1,079

7.7%

12,848

38,045

2.96

Darlington

Census 4-18-98

61,529

1,064

1.7%

26,108

2,524

9.7%

23,584

60,465

2.56

Census 4-1-90

61,851

1,054

1.7%

23,601

1,602

6.8%

21,999

60,797

2.76

Census 4-1-80

62,717

742

1.2%

21,504

1,444

6.7%

20,060

61,975

3.09

Fairfield

Census 4-18-98

22,284

426

1.9%

9,607

1,387

14.4%

8,220

21,858

2.66

Census 4-1-90

22,295

435

2.0%

8,730

1,263

14.5%

7,467

21,860

2.93

Census 4-1-80

20,700

293

1.4%

7,452

1,097

14.7%

6,355

20,407

3.21

Kershaw

Census 4-18-98

47,637

546

1.1%

20,453

2,221

10.9%

18,232

47,091

2.58

Census 4-1-90

43,599

409

0.9%

17,479

1,669

9.5%

15,810

43,190

2.73

Census 4-1-80

39,015

179

0.5%

15,243

2,112

13.9%

13,131

38,836

2.96

Lancaster

Census 4-18-98

55,212

1,528

2.8%

22,396

1,447

6.5%

20,949

53,684

2.56

Census 4-1-90

54,516

399

0.7%

20,929

1,151

5.5%

19,778

54,117

2.74

Census 4-1-80

53,361

277

0.5%

19,212

1,392

7.2%

17,820

53,084

2.98

Lee

Census 4-18-98

18,948

1,594

8.4%

7,128

710

10.0%

6,418

17,354

2.70

Census 4-1-90

18,437

153

0.8%

6,537

483

7.4%

6,054

18,284

3.02

Census 4-1-80

18,929

3

0.0%

6,138

539

8.8%

5,599

18,926

3.38

Lexington (Irmo)

Census 4-18-98

3,316

0

0.0%

1,173

34

2.9%

1,139

3,316

2.91

Census 4-1-90

4,080

0

0.0%

1,419

59

4.2%

1,360

4,080

3.00

Census 4-1-80

1,623

0

0.0%

535

33

6.2%

502

1,623

3.23

Marlboro

Census 4-18-98

26,380

1,200

4.5%

10,908

1,193

10.9%

9,715

25,180

2.59

Census 4-1-90

29,361

684

2.3%

10,955

792

7.2%

10,163

28,677

2.82

Census 4-1-80

31,634

215

0.7%

10,691

871

8.1%

9,820

31,419

3.20

Newberry

Census 4-18-98

32,238

806

2.5%

14,503

2,011

13.9%

12,492

31,432

2.52

Census 4-1-90

33,172

766

2.3%

14,455

2,141

14.8%

12,314

32,406

2.63

Census 4-1-80

31,242

742

2.4%

12,296

1,395

11.3%

10,901

30,500

2.80

Union

Census 4-18-98

27,734

283

1.0%

12,014

879

7.3%

11,135

27,451

2.47

Census 4-1-90

30,337

228

0.8%

12,230

823

6.7%

11,407

30,109

2.64

Census 4-1-80

30,751

105

0.3%

11,389

827

7.3%

10,562

30,646

2.90

Sources and Notes: See Table 4.
Note: The vacant units for the Lexington part of Irmo town for 1980 are not available in published tabulations; a
vacancy rate equal to the vacancy rate of Irmo as a whole (in Lexington and Richland) was assumed.

Table 6. Percent Distribution of Households by Number of Persons
per Unit and Average Number of Persons per Household (PPH) for Dress
Rehearsal Sites: 1980, 1990 and 1998

Persons per household

Site and Year

Number of
households

Percent Distribution by Size

PPH

1-3

4

5

6

7+

Sacramento City

1998

146,583

77.2

11.1

5.9

2.7

3.1

2.52

1990

144,444

77.8

11.4

5.6

2.6

2.6

2.50

1980

112,859

79.9

11.2

5.0

2.3

1.6

2.39

Menominee County

1998

1,356

60.3

12.1

13.2

6.3

8.1

3.36

1990

1,079

54.1

14.7

13.3

10.1

7.7

3.57

1980

799

44.8

17.7

10.7

9.3

17.5

4.22

South Carolina Site

1998

249,889

77.3

13.9

5.7

1.8

1.3

2.52

1990 [1]

232,076

73.4

15.5

6.7

2.4

1.9

2.67

1980 [1]

202,533

68.2

16.2

8.1

3.7

3.8

2.92

Note:
[1] Figures exclude Irmo town in Lexington County.

Source:
1998 Data : From Dress Rehearsal results available on Census Bureauís
Internet site (www.census.gov). The
census results for households do not
include a net undercount adjustment. The ICM adjustment is applied to
population totals only.
1980 and 1990 Data: 1980 and 1990 census tabulations. The data do not
include an undercount adjustment.

Table 7. Distribution of Population by Race for Dress Rehearsal
Sites: 1970, 1980, 1990 and 1998

Sources: 1998 data:. From Dress Rehearsal tabulations available on Census Bureauís Internet site
(www.census.gov). Results for Sacramento City and Menominee County include adjustment for net undercount.
1990 - 1970 data: From decennial census publications. The 1970-1990 data do not include an undercount
adjustment.

Table 8. Distribution of Population by Hispanic Origin for the
Dress Rehearsal Sites: 1980, 1990, and 1998

Total

Hispanic

Not Hispanic

Sacramento City, CA

1998

403,312

84,192

319,120

1990

369,365

60,007

309,358

1980

275,741

39,161

236,580

Menominee County, WI

1998

4,779

151

4,628

1990

3,890

55

3,835

1980

3,373

57

3,316

South Carolina Site

1998

662,140

12,727

649,413

1990 [1]

650,035

6,030

644,005

1980 [1]

626,393

7,420

618,973

Percent

Sacramento City, CA

1998

100.0

20.9

79.1

1990

100.0

16.2

83.8

1980

100.0

14.2

85.8

Menominee County, WI

1998

100.0

3.2

96.8

1990

100.0

1.4

98.6

1980

100.0

1.7

98.3

South Carolina Site

1998

100.0

1.9

98.1

1990 [1]

100.0

0.9

99.1

1980 [1]

100.0

1.2

98.8

Notes:
[1] Figures exclude Irmo town in Lexington County.

Sources:
1998 data: From dress rehearsal tabulations available on Census Bureau's
Internet site (www.census.gov).
Results for Sacramento City and Menominee County include adjustment for net
undercount.
1990 - 1980 data: From decennial census publications. The 1980-1990 data
do not include an undercount adjustment.

Sources:
Col. 1: Revised data from 1990 Census. Revisions include post-1990 Census
corrections of political geography or geographic mis-allocations and
boundary updates. Three counties in the South Carolina site are affected:
Chesterfield, Marlboro, and Richland.
Col. 2: From Post-Enumeration Survey estimates; consistent with estimates on
Census Bureau's PL94-171 file on Internet site.
Col. 5: Calculated by subtracting independent population estimates for 4-18-98
from revised 4-1-90 Census data (Appendix C Table 1: Col. 8 minus Col. 5).
See Appendix C Table 1 for derivation of population estimates for dress
rehearsal Census Day (4-18-98).
Col. 6: Independent population estimates for dress rehearsal Census Day
(4-18-98) adjusted for net undercount.
Col. 7: The 1998 census population estimates do not include the adjustment
for net undercount. These results for Sacramento City and Menominee
County are used for evaluation purposes only; the released census totals
that include the ICM component are shown in Table 1 (col.4).

Note: The housing and population data for Irmo town in Lexington County
are included in the South Carolina site total and ĎOthe Countyí total, but
are not shown separately

Table 10. Comparison of Number of Persons Enrolled in Medicare
and Persons Aged 65 and Over Enumerated in the Census: 1990 and 1998
(South Carolina Site)

County

1990

1998

Census:
Ages 65+
(1)

Medicare
Enrollment
(2)

Ratio

(3)=1/2*100

Census:
Ages 65+
(4)

Medicare
Enrollment
(5)

Ratio

(6)=4/5*100

South Carolina Site:

Site total

73,863

72,272

102.2

77,792

79,186

98.2

Richland county

26,888

27,324

98.4

29,983

30,818

97.3

Other counties (total)

46,975

44,948

104.5

47,809

48,369

98.8

Chester

4,258

4,153

102.5

3,885

4,255

91.3

Chesterfield

4,888

4,618

105.8

4,930

4,720

104.4

Darlington

7,370

6,843

107.7

7,757

7,478

103.7

Fairfield

3,021

2,705

111.7

3,100

2,889

107.3

Kershaw

5,238

5,742

91.2

6,337

6,788

93.4

Lancaster

6,657

6,006

110.8

6,940

6,670

104.0

Lee

2,232

1,936

115.3

2,394

2,243

106.7

Marlboro

3,733

3,553

105.1

3,314

3,521

94.1

Newberry

5,108

5,208

98.1

4,899

5,368

91.3

Union

4,470

4,184

106.8

4,253

4,437

95.9

Note: Figures exclude Irmo town in Lexington County

Sources:
Census data:
1990: From decennial tabulations.
1998 Data: Unpublished tabulations. The results do not include an
adjustment for net undercount.
Medicare data: From unpublished data from the Health Care Financing
Administration.

Table 11. Comparison of Number of Children Enrolled in School
(Grade 1 to 8) and Children Ages 7-14 Enumerated in the Census: 1990 and
1998 (South Carolina site)

Sources:
Census data:
1990: From decennial tabulations.
1998 Data: Unpublished tabulations. The results do not include an
adjustment for net undercount.
School enrollment data:
Public school enrollment is from South Carolina Dept. of Education.
Private school enrollment is from Census Bureau survey of all private
schools.

Table 12. Demographic Estimates of Percent Net Undercoverage
and Coverage for Children Under Age 10: 1990 and 1998 (South Carolina
Site)